Quigley says CCC investigating evidence tampering

The shadow Attorney-General, John Quigley, has described allegations of misconduct against WA Police over a murder conviction in 2007 as 'a very serious perversion of justice'.

The Corruption and Crime Commission (CCC) is investigating possible evidence tampering at the scene of a 2007 murder in the south-west.

Scott Douglas Austic was sentenced to 25 years in jail for the wilful murder of Stacey Thorne after she died of multiple stab wounds at her Boddington home

Mr Quigley says the CCC is investigating claims a cigarette packet stained with Ms Thorne's blood is visible in later crime scene photos but not the originals.

"Who put the packet of cigarettes with the blood smudge, there is the first big question of this investigation," he said.

He says a number of grave errors by the Attorney-General, Michael Mischin, have stood in the way of justice.

"His delay, his referring of allegations of police misconduct back to the police to investigate, his failure to forward the complaints to the CCC and his failure to refer this matter back to the chief justice's Court of Appeal," he said.

Mr Mischin says he acted as soon as he became aware of the allegations.

"There's due process to be followed and I've been following that process," he said.

"And, I'm not of a mind to refer cases to courts of appeal simply on his say so I need to be satisfied whether a case should be reopened in that fashion."